Simplify the following expression: $a = \dfrac{-z + 2}{2z + 3} + \dfrac{-6z}{2z + 3}$
Since the expressions have the same denominator we simply combine the numerators: $a = \dfrac{-z + 2 - 6z}{2z + 3}$ Combine like terms: $a = \dfrac{-7z + 2}{2z + 3}$